Simplify the following expression: $k = \dfrac{x^2 - 9x + 18}{x - 6} $
Explanation: First factor the polynomial in the numerator. $ x^2 - 9x + 18 = (x - 6)(x - 3) $ So we can rewrite the expression as: $k = \dfrac{(x - 6)(x - 3)}{x - 6} $ We can divide the numerator and denominator by $(x - 6)$ on condition that $x \neq 6$ Therefore $k = x - 3; x \neq 6$